Morphology-optimized ZnSnO3 nanopentagons as efficient electron transport layers for high-efficient perovskite solar cells

Ternary metal oxides with high optical transparency and wide bandgap semiconductors have gained significant attention as promising candidates for various optoelectronic device applications. In this study, ZnSnO₃ nanomaterials, synthesized in distinct nanopentagon and spherical nanoparticle morphologies, were prepared using hydrothermal and microwave-assisted synthesis methods. Structural analysis through X-ray diffraction (XRD) confirmed the perovskite phase of ZnSnO₃. Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) revealed distinct morphological variations, while Energy Dispersive Spectroscopy (EDS) mapping validated the stoichiometric composition. X-ray Photoelectron Spectroscopy (XPS) further confirmed the oxidation states of Zn²⁺, Sn⁴⁺, and O²⁻. Optical studies from Ultraviolet–visible spectroscopy (UV–Vis) revealed bandgap values of 3.64 eV and 3.66 eV for ZnSnO₃ synthesized via hydrothermal and microwave methods, respectively. To evaluate their performance in optoelectronic applications, ZnSnO₃-based electron transport layers (ETLs) were incorporated into an FTO/ZnSnO₃/CH₃NH₃PbI₃/Spiro-MeOTAD/Au perovskite solar cell architecture. Notably, hydrothermally synthesized ZnSnO₃ nanopentagon ETLs achieved a power conversion efficiency (PCE) of 17.73 %, outperforming the 14.28 % PCE obtained with microwave-synthesized spherical nanoparticles. This study underscores the potential of ZnSnO₃-based ETLs for highly efficient perovskite solar cells (PSCs), emphasizing the impact of synthesis methods on device performance. By demonstrating the viability of ZnSnO₃ nanomaterials in advanced optoelectronic applications, this work lays the groundwork for further optimization and development of high-performance devices leveraging ternary metal oxides.